--- /dev/null
+#include_file "core/std/wasi"
+
+use package core
+use package core.string.reader as reader
+
+TILE_DATA_WIDTH :: 10
+TILE_DATA_HEIGHT :: 10
+
+Tile :: struct {
+ id : u32;
+ orientation : TileOrientation;
+ data : [] bool;
+ edges : [] u32;
+
+ pos_x : u32 = 0;
+ pos_y : u32 = 0;
+
+ edges_with_match : Sides = Sides.{};
+}
+
+Sides :: struct {
+ top : bool = false;
+ right : bool = false;
+ bottom : bool = false;
+ left : bool = false;
+}
+
+TileOrientation :: enum {
+ NORMAL; ROTATE_90; ROTATE_180; ROTATE_270;
+ FLIPPED_NORMAL; FLIPPED_ROTATE_90; FLIPPED_ROTATE_180; FLIPPED_ROTATE_270;
+}
+
+// Thought about making this dynamic and really fancy...
+// and then I remembered this is advent of code so that
+// is not necessary.
+TileData :: #type [TILE_DATA_WIDTH * TILE_DATA_HEIGHT] bool;
+
+reverse_binary :: proc (n_: u32, digits := TILE_DATA_WIDTH) -> u32 {
+ res := 0;
+ n := n_;
+ for _: 0 .. digits {
+ res <<= 1;
+ res |= (n & 1);
+ n >>= 1;
+ }
+
+ return res;
+}
+
+build_edges :: proc (tile: [] bool, a := context.allocator) -> [] u32 {
+ edges : [] u32;
+ #context_scope {
+ context.allocator = a;
+ alloc.alloc_slice(^edges, 8);
+ }
+ next_edge := 0;
+
+ for y: u32.[0, 9] {
+ edge := 0;
+
+ for x: 0 .. 10 {
+ edge <<= 1;
+ if tile[x + y * TILE_DATA_WIDTH] do edge |= 1;
+ }
+
+ edges[next_edge] = edge;
+ next_edge += 1;
+ }
+
+ for x: u32.[0, 9] {
+ edge := 0;
+
+ for y: 0 .. 10 {
+ edge <<= 1;
+ if tile[x + y * TILE_DATA_WIDTH] do edge |= 1;
+ }
+
+ edges[next_edge] = edge;
+ next_edge += 1;
+ }
+
+ for i: 0 .. 4 {
+ edges[next_edge] = reverse_binary(edges[i]);
+ next_edge += 1;
+ }
+
+ return edges;
+}
+
+has_matching_edges :: proc (t1: ^Tile, t2: ^Tile) -> bool {
+ match := false;
+
+ for e_idx: 0 .. t1.edges.count / 2 do for e2: t2.edges {
+ if t1.edges[e_idx] == e2 {
+ match = true;
+
+ switch e_idx {
+ case 0 do t1.edges_with_match.top = true;
+ case 1 do t1.edges_with_match.right = true;
+ case 2 do t1.edges_with_match.bottom = true;
+ case 3 do t1.edges_with_match.left = true;
+ }
+ }
+ }
+
+ return match;
+}
+
+main :: proc (args: [] cstr) {
+ contents := file.get_contents("input/day20.txt");
+
+ file := reader.make(contents);
+
+ tiles : [..] Tile;
+ array.init(^tiles);
+ defer array.free(^tiles);
+
+ tile_data := calloc(200 * sizeof TileData);
+ defer cfree(tile_data);
+
+ tile_data_arena := alloc.arena.make(tile_data, 200 * sizeof TileData);
+ tile_allocator := alloc.arena.make_allocator(^tile_data_arena);
+
+ while !reader.empty(^file) {
+ reader.read_word(^file); // 'Tile '
+ id := reader.read_u32(^file);
+
+ reader.advance_line(^file);
+
+ td := cast(^bool) raw_alloc(tile_allocator, sizeof TileData);
+
+ for y: 0 .. 10 {
+ line := reader.read_line(^file);
+
+ for x: 0 .. 10 {
+ td[x + y * TILE_DATA_WIDTH] = (line[x] == #char "#");
+ }
+ }
+
+ tile_data := td[0 .. TILE_DATA_HEIGHT * TILE_DATA_WIDTH];
+ edges := build_edges(tile_data, tile_allocator);
+
+ array.push(^tiles, Tile.{
+ id = id,
+ orientation = TileOrientation.NORMAL,
+ data = tile_data,
+ edges = edges,
+ });
+
+ reader.advance_line(^file);
+ }
+
+ prod: u64 = 1;
+
+ for i: 0 .. tiles.count - 1 {
+ matching_count := 0;
+
+ for j: 0 .. tiles.count {
+ if i == j do continue;
+ if has_matching_edges(^tiles[i], ^tiles[j]) {
+ matching_count += 1;
+ }
+ }
+
+ if matching_count == 2 {
+ prod *= ~~tiles[i].id;
+ }
+ }
+
+ printf("Corner product: %l\n", prod);
+}
projects / onyx-aoc-2020.git / commitdiff